The present invention relates to improvements in an airbag module for vehicles, and more particularly to a reinforcement structure for an airbag of the airbag module, and a method of producing the reinforcement structure.
Many motor vehicles are equipped with an airbag module for protection of a passenger upon occurrence of accidental collision. Examples of such an airbag module are disclosed in Japanese Patent Application Second Publication No. 56-43890, Japanese Patent Application First Publication No. 2-200548 and Japanese Utility Model Application First Publications Nos. 54-69543 and 61-85549.
The airbag module includes an airbag which is supplied with gas for inflation thereof. As an example, such an airbag may be made of a plurality of segments of a sheet material which are stitched together to form a bag body. One of the segments is provided with a reinforcement structure for attachment of the airbag to a gas generator or a stationary member of a vehicle body. The gas generator is adapted to momentarily generate gas under a predetermined condition so that the airbag is deployed by the gas pressure. The reinforcement structure is constituted by a substantially rectangular reinforcing member which is also made of a sheet material and stitched to a bag body segment in an overlaying relationship. As a result, the reinforcing member has two pairs of rows of stitching which extend along opposite edges thereof to traverse each other at the corners thereof.
In a stitching step of manufacturing such an airbag, when the second pair of the rows of stitching is formed after forming the first pair, a corner portion of the reinforcing member tends to be folded upon itself and sewed thereto. The folded corner portion of the reinforcing member has a reduced strength against mechanical force applied thereto.
An object of the present invention is to provide a vehicle airbag which is readily manufactured without sewing problems such as folding of a corner portion upon itself, and which has sufficient strength against mechanical force applied thereto.